Near-Infrared Light-Driven Photocatalytic Antibacterial Activity of CaCO ₃ /C/PDA Nanocomposites against Gram-Negative Bacteria

Antibacterial resistance has become a growing global health challenge, with multidrug-resistant pathogens posing significant threats to public health. Traditional antibacterial agents often encounter problems such as high costs, low efficiency, poor antibacterial efficacy, and restricted biocompatibility. Thus, there is an urgent need to develop materials with enhanced antibacterial properties. In this study, CaCO₃/C/PDA antibacterial composite was designed as a high-efficacy antibacterial agent against Gram-negative bacteria. Under near-infrared light irradiation (808 nm, 0.3 W/cm², 4 min), the CaCO₃/C/PDA^0.2 exhibited satisfactory antibacterial activity against Gram-negative bacteria, including <i>Escherichia coli</i>, <i>Pseudomonas aeruginosa</i>, and <i>Klebsiella pneumonia</i>, with sterilization rates of 91.7%, 98%, and 100%, respectively. The antibacterial mechanism could be attributed to the synergistic effects of photothermal and photodynamic therapy, where high temperatures can denature bacterial proteins and reactive oxygen species (ROS) may disrupt bacterial metabolism, ultimately leading to bacterial death. All of the experimental results confirmed that CaCO₃/C/PDA is a promising antimicrobial agent for Gram-negative bacterial infections. In addition, the <i>in vitro</i> toxicity tests also confirmed that CaCO₃/C/PDA possessed excellent biocompatibility. Overall, this work offers an approach and strategy for the development of next-generation antimicrobial materials with broad biomedical potential.